When Gus the Big Mean Bunny & I wanted a dog but couldn't (for the same reasons -- working crazy and unpredictable hours, no garden, etc.), we got a guinea pig instead. He wanted a cat, but at that time I was a decidedly anti-cat person and utterly refused, so we got the largest rodent that was not a rabbit we could find (we both hated rabbits).

And Perkins was a wonderful pet (see icon) and I miss him still, but he wasn't really a dog and didn't do much to fill the dog-shaped hole we had.

I would suggest that if you want a lizard, get a lizard, but if you want a dog, don't expect a lizard to do.